Indicator for electric fuses



Apr. 3, 1923.

- F. c. LA MAR INDICATOR FOR ELECTRIC FUSES Filed June '7, 1920 FRAN ATTORNEY.

' 35 faras l'am aware,

' v1de an indicator for electric fuses which Patented A pnf3, 1923.

LuNlTEo STATES TIE NT e u-1..

- rm'x m, or rrr'rsnuaan, mmmm;

I inmca'roa roa wi dness.- l

ima med wit 7, 1820. Serial No. 7,017.

To all whom. it may mm lowing isa' specification.

-. This invention relates to electric; fuses.

The object of the invention is to provide such fuses with an indicating device or at'- tachment, whichis simple and economical in construction, and also efiicient and positive in operation, and the purpose of which- 16 is to positively notify an operator or attendant whether the circuit in which the fuse is placed as a protecting medium is open or closed, and thereby avoid all danger of injury to the, operator or attendant from 20 electricshock "in attempting to repair or ad just the machinery 0 rated by the current passing through the use and also to notify the operator or attendant when the fuse is blown-out so the fuse may be removed for refilling or reloading without danger of shock, and also avoid loss of time and delay in locating a particular fuse which has blown-out orbecome ruptured in service.

Another object of this invention is to pro- 80 vide an indicator for an electricfuse which is permanent and continuous in operation and needs no repair or replacement of parts, a 'difiiculty which is common in the indicators now in use on some ty es of electric fuses.

am the first to proconstitutes a..permanent attachment for the fuse and which willjcontinuously indicate f positively .the flow, or interru tion of ourlarly desi ed'for use in connection with 'what are' own as refillable fuses and is 1 applicable to any of the well knownfuses of thisjtype, and I-haveshown herein them- 'dicator forming the sub ect of'this invenition applied to'a} refillable fuse of the construction and principle of that type descr' d and claimed in my co pending appli-' cat on filed 'June 3, 1920, Serial No. 386,280.

The present invention consists in an elec forth ,and finally claim.

- tric fuse, comprising casing, .a fuse element secured in said casing, and an electric indi cator for indicating the flow and interruption of current through the fuse connected in circuit with the fuse element'and adapted to be operated by the maldng and breaking of the'current passing through the fuse whereby the on and ofi conditions of the-current of the working circuit is successively and continuously indicated.

The invention also consists in an electric fuse comprising a casing, a fuse element fixed in end casi-ri and-an electro-ma eticallybperated. in icator for indicatin the flow and interruption of the current through the fuse, connected in circuit with the fus e element between its terminals and adapted to be operated by the making and breaking of the current passing through the fuse, whereby the on and oil conditions of the working current is successively and continuously indicated.

The invention also consists in the details of construction and combination and ar-' rangement or locationof arts as herein' shown and described, all su stantially as I will priiceed now to more particularly set In the accompanying drawings, illustrating the invention, in the several views of which like parts are similarly designated, Figure 1 is an elevation of an assembled fuse showing the indicating opening in thecasarrows Fig. 4 'isa perspective view of the indicator plate and its "attached armature. F1g'.'5 is a detail view-showing a'm odified connection between the fuse element and the electro-magnet o'r solenoid,-and Fig. 6 is a detail view, in cross section of the casing and the fuse element fixing plug, showing one form of means for securing the fuse-element .fix'ing plug in the casing and sealing the Asfshownin the drawings, the fuse, as in Y my application above mentioned, comprises a-cas1ng I having screwthreaded ends 2, end caps 3 fitted uponsaid screwthreaded ends, a main fuse element fi-xedin a block of insulating material pemanentlyfitted' within the casing, and removable fuse elements titted upon blocks and inserted in the ends of the casing and contacting with the terminals of the main fuse elements, and held in place by the end caps. the main fuse element being of greater conducting capacity than the removable end fuse elements, whereby in case of an excess current passing through the fuse the removable fuse elements will be ruptured or burned out, leaving the main fuse element -to be screwed upon the casing and also adapted to be punched at one or more places,

as at 5, after being screwed to place to more securely lock the ferrule against rotation upon the casing.

In my application referred to I have 1 shown the blocks 6'for supporting and an:

choring the removable fuse elements 7 in the endsof the casing with a tongue and groove connection with the casing to prevent them from turning in the casing, and have herein shown the beveled and contacting portions 8 and 9 of the blocks and the main fuse plug at a greater angle than that in my said application which construction will effectively prevent rotation of the blocks, instead of the tongue and groove connection.

In the construction herein, and for the purposeof this invention, the main fuse element carrying and supporting plug 10, which as in my application above mentioned 7 is permanently secured in the casing, is

formed with a; recess 11 opening upon one side of the plug, and the bottom of which is provided with a sunken rounded seat 12 to receive and support a solenoid or electromagnet 13, including a movable core or armature 14 backed up at one end by 'a coiled.

spring 15, seated in a socket 16 in one of the end walls of the recess of the plug and normally projecting the movable corev or a'r-- mature into engagement with the opposite end wall of the recess. Secured to the outer and of the movable core or armature 14, as

by riveting or otherwise, is an indicatingplate 17 which as herein shown is of curved form to coincide with the contour of the interior of the casing-and overhangs the solenoid or magnet and is .provided with a depending portion"1 8 by which it is'secured to the movable core of the solenoid. The plate 17 is provided upon its'upper surface with two distinctive colors? spaces or portions, 19 and '20, .such as blac and red, respectively,

to be exposed at an opening 21 in the casing to indicate on. and off. or the plate may be provided with anv other suitable marks for indicating the on and off conditions. In

'the present illustration the black will indicate off and the red. will indicate "on.

The terminals 22, of the solenoid winding may be electrically connected with the main fuse elements 23 in any suitable manner, preferably by soldering, as at 2%. and the winding of the solenoid ma be of the same carrying capacity as the main fuse elements and thus'form part of the main fuse element, and in this case the entire solenoid or coil would be destroyed or burned out should the fuse be subjected to an overload by reloading the fuse with removable end fuse elements of greater capacity than the main or permanent fuse element. Therefore, it is desirable or pyeferableto provide the solenoid with a windingof greater carrying capacity than the main fuse portions 23 and solder or otherwise connect the winding with these fuse portions, so that in case-of a blow out by overloading thefuse with removable end fuses, the portions 23 of the fixed fuse element only will be burned out or ruptured to open the circuit, and the solenoid and other parts of the indicating mechanism remain undamaged for removal from the otherwise damaged and unrepairable fuse,

for further use in' building other fuses.

In my application hereinbefore referred to, it is stated that the main fuse element supporting plug is permanently and immovably secured in the casing-for the purpose of preventing the reuse of the fuse after the occurrence of a blow out of the main fuse element on account of overloading, and in order to provide for the removal of the solenoid. and indicating mechanism of the con-- struction herein, as above stated, the main fuse plug may, as shown in Fig. 6, to be fixed in the casing by drilling a hole through the casing and into the plug as at 25 to receive a screw 26 and countersinking the casing about the hole, asat 27 ,to receive the head of the screw, and filling the countersink with sealing wax or other hardenlng material 28, to seal the fastening against ready removal by unauthorized persons, but per-' mitting removal of the fastening screw by breaking out the sealing material when it is desired to remove the plug and the undamaged indicating mechanism from an otherwise damaged and useless fuse, for the pur-v I pose hereinbefore stated.

In Fig. 5, I have shown a diagrammaticview of a modified arrangement of the mainfuse element and solenoid, in whicha resistance 29 is shunted around the solenoid so that the full current from the supply source willnot enter the solenoid winding, and the capacity of this resistance may He adjusted to suit the desired capacity of the solenoid stood from the above description in connection with the description thereof in my application referred to, and it will 'be observed that when the fuse is installed and the. circuit in which the fuse is placed is turned on, the magnet or solenoid 13, will be energized and draw in the armature core 14 and its attached indicating plate 17 so the red portion 20 thereon will coincide with the opening 21 in the casing, thereby indicating that the current is on, the core in its inward moveinent compressing the spring 15, and the outer enlarged end of the core engaging the end of the coil and serving as a stop to limit the inward movement of the 'core and properly position the red portion of the indicator plate at the opening in the casing. When the current is turned off, the magnet or solenoidwill be deenergized, and the spring 15 will force the core outwardly and the black portion of the indicating plate will'be-moved opposite the opening in the casing, thus indicating that the current is off. The core in its outward movement will abut against the end wall of the recess in the plug 10 and serve as a stop to limit the outward movement of the core and thus hold the platewith its'black portion at the opening irithe casing. It will thus be seen, that when the service current is switched on and ofi, the indicator will alternately andcontinuously indicate the on and off conditions of the current, thereby avoiding all danger of accidents occurring by not knowing-whether the current'is on or off in any particular line or circuit in which the fuses are placed.

In case of a blow out. at'the end fuse elements, the magnet or solenoid will become deenergized andthe indicator moved to the off position and thus indicatethat the current in this particular circuit of any number of circuits that lead into a switch box has been subjected to an overload, and thereby enabling an operator to readily locate any trouble in his installation and avoid any delays in the running of his machines by reloading the thus readily located blown out fuse.

In the case of a fuse being refilled with end fuse elements of a load capacity greater than the main fuse element or elements, and

an excess or overload current enter the fuse,

then the main fuse element would'burn out and break or interrupt the current andjthe solenoid or magn t ene giz dand' the'- indicator moved to oif position and-"remain in that osition if the {current be again turned on, t us indicat ii gijthat the ma n fuse element has been destroyed and the fuseabsO- lutely dead and unrepairable or refillable.

Thus it will be observed that I have provided an indic'ator for electric fuseswhich is tion continuously positive in operation and repeats its operaso long as the fuse is in operative conditlon, and an indicator-which is particularly useful in connection with enclosed fuses of the refillable type, whereby the danger of accidents and long delays in parts herein shown and described, "as the same may be changed or altered'in various particulars and still be within the scope of the appended claims' What I claim is 1. An electric fuse, comprising a casing, a

fuse element fixed in said casing, and an electrically operated movable indicator for said fuse connected in circuit with said fuse element, adapted to be controlled by the current passing through said fuse element to continuously and alternately indicate the on and off conditions of the current.

fuse element fixed in said caslng, and an electrically operated movable indicator for said fuse connected in circuit with said fuse element between the terminals thereof v 2. An electric fuse, comprising a casing, a 1

and adapted to be permanently controlled by the current passing through said fuse element to alternately indicate the on and off conditions of the current.

3. An electric fuse, ;comprising a'casing,

a fuse element fixed in said casing, and an electro-magnetically operated movable indi- 1 cator for said fuse connected in circuit with said fuse element and adapted to be continuously and permanently controlled by thecurrent passing throughsaid fuse element to alternately indicate the on and off conditions of the current.

4. An electric fuse, comprising a casmg having an opening therein, a fuse element fixedin said casing, and an electro-magnetically operated indicator arranged in the caslng and connected in circuit with the fuse element and adapted to be operated by the current passing throu h said fuse element to continuously and a ternately expose off and on current conditions at the opening in saidcasin v 5. An electric fuse, comprising a casing having an opening therein,, a fuse element fixed in said casing, a solenoid arranged in said casing and 'connected in circuit with Ill said fuse element, a movable core in said solenoid, an indicator plate attached to and carried by said core and located adjacent to 1 the opening in said casing and having distinctive marks thereon, the movement of said coreada ted to be-controlled by the make and brea of the circuit passing through said solenoid to cause said plate to alternately expose the distinctive marks thereon at the opening in said case, to indicate the on and off conditions of the current passing through the fuse.

6. An electric fuse, comprising a casing having an opening therein, a fuse element fixed in said'casing, a solenoid arranged in the casing and connected in circuit with said fuse element, a movable core in said solenoid, an indicator plate attached to and carried by said core and located adjacent to the opening in said casing and having on and off indications thereon, the said core adapted to be operated by current passing through said solenoid to move the plate to expose its current on indication at said opening, and a spring for moving said core and plate to expose the current-off indication at opening in said casing and having on'andofi' indications thereon, the movements of said core adapted to be controlled by the make and break of the circuit passing through said solenoid to cause the plate to expose its current on indication at said opening means to return the indicator to its off position when the circuit is broken and means for limiting the movements of said core and its attached indicating plate in both directions to properly position the indicating marks with relation to the opening.

8. An electric fuse, comprising a casing, a fuse element fixed therein, an electrical y operated indicator connected in circuit with said fuse element and adapted to be operated by -the making and breaking of the circuit passing through said fuse element, to indicate the on and off conditions of the current, and a resistance connected with said fuse element and shunted around said electrically operated indicator.

9. A- refillable electric fuse, comprising a casing, a plug fitted in said casing. a main fuse element fixed in said plug and having its terminals exposed at the opposite ends thereof, an electrically operated indicator fixed in said plug and connected in circuit with the main fuse element, a screw passing through the casing and engaging said plug and having its head entering a countersink in said casing, a sealing material secured in said countersink and concealing the head of the screw to prevent ready removal of the screw and permanently securing the plug in said casing. removable fuse elements adapted to be inserted in the ends of the casing'and contacting with the terminals of the main fuse element, and means for holding said removable fuse elements in place, the said sealing material adapted to be ruptured and removed, whereby said fastening screw may be removed and the main fuse plug and its attached indicating mechanism removed from the casing.

10. A refillable electric fuse, comprisinga casing, a plug fitted in said casing, an electrically operated indicating mechanism fitted in a recess in said plug within the casing and being'of a certain rated or predetermined elements-will be blown by an excess cur- 7 rent passing through the fuse without injury to the indicating mechanism. 1

In testimony whereof I hereunto set my hand this 7th day of June 1920.

FRANK C. LA MAR. 

